New pipe Nipple size question

jbmoff

Good Morning,

I recently noticed that ~7" nipple on a 2" wet return on my steam boiler is leaking and needs to be replaced. It ties into a 90* elbow on one end and a union on the other. I am trying to figure out the exact size nipple replacement that will engage enough threads on both sides/ends. I know there was a chart somewhere that detailed this, but wondering if there was a quicker rule of thumb.

STEAM DOCTOR

Need a little bit more information here. If you will be using unions and the like, the old nipple length will not be that relevant. Because the union will take up space. Some pictures will be helpful. You can always get a union or two, and a run of nipples.

STEAM DOCTOR

Sometimes, it's easier to cut out further back. Gives you more wiggle room. Are you sure this is 2" pipe?

jbmoff

The current nipple sits between a 90 elbow and a union. I just need to unscrew the union, and remove the nipple from the union and the 90….or cut it out. I was almost going to just measure the current one when I remove it to size the replacement.

ethicalpaul

A picture of this return entering your boiler is worth 1,000 words

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1896862#Comment_1896862

and why, exactly, won't that work?

jbmoff

Ha! It should, right? I was hoping to know a correct nipple size to have on hand before I cut the old one out.

I just thought there was a "formula" to know the make up lengths for ends of nipples when joining pieces.

mattmia2

they are manufactured in 1/2' or 1" increments depending on the length so if it is a factory made nipple you can hold a folding rule or tape up next to it and imagine where it is inside the fittings and figure out what length it is, if it wasn't cut to a custom size.

Intplm.

@jbmoff I'm thinking that your measurement of a seven-inch nipple is the installed length, and you are measuring the installed length? Is that correct? If so, you probably have an eight-inch nipple or, more accurately, a 2" x 8" nipple.

The threads have been screwed into the two fittings by about 1/2" on each side, confirming your installed measured length of 7" as previously stated. This should explain and help with a "Quicker rule of thumb" as originally asked in your post. So, you probably need a 2 x 8-inch nipple. Hope this helps.

JUGHNE

Often if you have one leak, another is not far behind.

You may find that as you remove that nipple, just putting wrenches on the union may create another leaker.

Again, pictures would help.

And if that is a custom cut length of pipe, I have used two nipples with a coupling in-between the nipples. This gives you 4 sets of threads to muscle around to get the correct length.

jbmoff

That's pretty much exactly what I was asking! Thanks so much for that quick and succinct response! And thank you everyone else for your inputs!

mattmia2

https://forum.heatinghelp.com/discussion/comment/1896883#Comment_1896883

in most cases there is enough play that the closest half inch or even inch is close enough.

EBEBRATT-Ed

@jbmoff

Give or take a little but 2"pipe will thread in about 5/8" on each end. It does vary a little especially with the quality (not) of the fittings made today.

Nipples are manufactured in 1/2" increments from close (the shortest nipple) to 6". Over 6" they are in 1" increments.

As @jughne pointed out 2 nipples with a coupling can give you more adjustability.

Lets say a nipple cranks in 5/8" to be tight. It probably will not leak it is 1 turn looser or it could be tightened 1 more turn beyond tight.

2 nipples give you more give and take